Method and arrangement for utilizing a psuedo-alloy composite for rapid prototyping and low-volume production tool making by thermal spray form techniques

ABSTRACT

Method and arrangement for spray forming an article. The method includes spraying a plurality of metal streams upon a low-heat resistant model and thereby forming a spray formed article. Each of the plurality of metal streams is composed of moltenized droplets, and as between the plurality of metal streams, each is composed of different constituent elements. In the spray form process, conditions of the metal streams are controlled, particularly around the time that the droplets land, to prevent adverse affects such as melting or burning the master model. The spray conditions are controlled in such a manner that the individual metal droplets forming the metal streams remain substantially segregate. The segregated state is maintained through out solidification so that the resulting spray formed article is composed at least partially of psuedo-alloy.

BACKGROUND OF THE INVENTION

[0001] There are many situations in which it is desired that a prototypeor low-volume production tool be made from a master model constructedfrom relatively low heat-resistant material; that is, the material outof which the model is constructed either softens and/or melts at arelatively low temperature, or is combustible at comparatively lowtemperatures. Examples of such materials of construction for mastermodels that would be desirably accommodated include wax, wood, plasticand similar materials.

[0002] It is known to use zinc alone in spray forming processes on suchlow heat-resistant materials, but the resulting tool is relatively softbecause of its exclusive, or near-exclusive zinc content. As a result,tools of only very limited application may be formed in such a manner.These tools are normally limited to prototype applications because theydo not possess sufficient durability to withstand even low-volumeproduction manufacturing.

[0003] Conventional thermal spray form molding has utilized metals whichrequire substantial energy input, which is typically manifest as heatenergy, to moltenize and make the metal sprayable. Because of the hightemperature of such a moltenized metal when it strikes the master model,the model has typically been required to be constructed from high heattolerant material, such as ceramic, in order to survive the spraying ofsuch molten metal thereupon. Because the original model is not typicallycast directly in ceramic, multiple steps are required to finallyestablish a ceramic master model from one that has been constructed, forinstance, by rapid prototyping methods such as stereo lithography, orwhich are constructed out of other types of low-heat resistant materialssuch as wood, wax and plastic laminate.

[0004] Because of the expense and delay associated with the usualmulti-step process required to establish the ceramic master model, it ishighly desirable to be able to perform spray form techniques directlyupon the surface of an original model constructed from such rapidprototyping methods and low-heat resistant materials.

SUMMARY OF THE INVENTION

[0005] In at least one embodiment, the present invention takes the formof a method for spray forming an article, such as a low-volume stampingtool. The method includes spraying a plurality of metal streams upon alow-heat resistant model and thereby forming a spray formed article.Each of the plurality of metal streams is composed of moltenizeddroplets, and as between the plurality of metal streams, each iscomposed of different constituent elements. According to the invention,conditions of the metal streams are controlled, particularly around thetime that the droplets first land, to assure that excessive heat energycontained therein is for all practical purposes, dissipated essentiallyimmediately upon contact. In this way, if there is heat imposed on themodel from the sprayed metal, it is sufficiently transitory that evenlow-heat resistant materials remain unaffected. The spray conditions arecontrolled in such a manner that the individual metal droplets formingthe metal streams remain substantially segregate; that is to say,touching one another, but without intermixing across droplet surfaceboundaries. The droplets are held together based on mechanical adhesionthat occurs when the semi-molten droplets come into contact with oneanother.

[0006] The segregated state is maintained through out solidification sothat the resulting spray formed article is composed at least partiallyof psuedo-alloy; that is, commingled droplets of different elementalmetals, but without intermixing into true alloys. The article may alsobe considered a psuedo-alloy based on a more global perspective; thatis, the individual droplets may not be highly commingled, but differentelemental deposits that are established in the spraying process areintermingled.

[0007] In another aspect, the invention includes the control of therelative proportions utilized of each of the metal streams that aredifferently composed on an elemental basis in a manner that institutesprescribed performance characteristics in the resulting spray formedarticle. In this way the qualities of the finished spray formed productcan be manipulated to assure that the article is suitable for itsintended use; as an example, as a spray formed stamping toolmanufactured for use in low-volume production processes.

BRIEF DESCRIPTION OF DRAWINGS

[0008] The invention will now be described in greater detail in thefollowing way of example only and with reference to the attacheddrawings, in which:

[0009]FIG. 1 a schematic representation of a spray form arrangementconfigured according to an embodiment of the present invention.

[0010] FIGS. 2A-2D illustrate depositional outcomes produced when aplurality of arc guns are aimed for adjacent, but spaced-apartdepositional patterns according to the teachings of the presentinvention.

[0011] FIGS. 3A-3D illustrate depositional outcomes produced when aplurality of arc guns are aimed for segregated, but touchingdepositional patterns according to the teachings of the presentinvention.

[0012] FIGS. 4A-4D illustrate depositional outcomes produced when aplurality of arc guns are aimed for overlapping depositional patternsaccording to the teachings of the present invention.

[0013] FIGS. 5A-5D illustrate depositional outcomes produced when aplurality of arc guns are aimed for substantially commingleddepositional patterns according to the teachings of the presentinvention.

DETAILED DESCRIPTION

[0014] As required, detailed embodiments of the present invention aredisclosed herein; however, it is to be understood that the disclosedembodiments are merely exemplary of the invention that may be embodiedin various and alternative forms. The figures are not necessarily toscale, some features may be exaggerated or minimized to show details ofparticular components. Therefore, specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, butmerely as a basis for the claims and as a representative basis forteaching one skilled in the art to variously employ the presentinvention.

[0015] As described herein, and as shown in the accompanying drawings, acommon method for establishing thermal spray formed bodies utilizestwo-wire arc gun technology. In such a gun 13, two metallic wires 28,28or 31,31 are fed therethrough and sufficiently electrified so that anelectric arc is established between the wires, one each acting as ananode 19 and cathode 22. The arc produced is of sufficient power toinput enough heat energy to cause both wires 28,28 or 31,31 to be meltedand become molten. Using air jets 16, the moltenized wire 28,31 ispropelled in streams toward a target.

[0016] By conventional arrangement, each of the two wires 28,28 or 31,31of the arc gun 13 are fed by a pair of rotating wheels that are commonlygeared. As a result, the two wires 28,28 or 31,31 are fed atsubstantially the same rate through the arc. This makes it difficult, ifnot impossible, to feed two wires 28,28 or 31,31 in the same gun 13 thathave substantially different physical properties, especially withrespect to melting point. For instance, if one wire requiressubstantially more heat-energy to become molten than does the other, thewire with the higher heat requirement would necessarily have to be fedmore slowly through the arc. Conversely, the wire of lower heatrequirement for moltenization is often referred to as having a “quickerburn rate” than the higher melting point wire. The quicker burning wirewith the lower melting point can actually burn backwards away from thearc toward the gun if the feed speed is geared for the slower burning,higher melting point wire. As a result, undesirable sputtering andmisdirection of the molten metal can occur.

[0017] In order to take advantage of superior qualities that areproduced in a tool resulting from thermal spray form techniques thatutilize wires of different composition, the present invention employs aplurality of guns 13. That is to say, at least two guns 13 are utilized,but in a preferred embodiment, four guns 13 are utilized.

[0018] As background, the wire(s) 28 and 31 utilized in the presentinvention are supplied as off-the-shelf products. In addition tomanufacturing wire that is comprised of predominantly one element as isutilized in at least one aspect of the present invention, these samesuppliers normally also provide alloy wire, such as a zinc/coppercombination that is effectively wire composed of the alloy brass. Thecomposition of this type of alloy-wire is necessarily limited by theacceptable proportions for forming the alloy brass. The presentinvention, however, utilizes different metal-type wire 28 and 31 in eachof the different guns 13, but the wires 28,28 or 31,31 in any given gun13 are alike and often predominantly mono-elemental. As an example, in atwo gun 13 arrangement as illustrated in FIG. 1, zinc wire 28 might beutilized in one gun 13 while copper or steel wire 31 is utilize in theother. Since an actual alloy is not prescribed to be formed according tothe present invention, a much wider range of compositional combinations,as well as a wider array of possible resulting characteristics in thespray formed body are achievable. The guns 13 are shown to be atdifferent depositional stages or volumetric rates; that is, moremoltenized wire 31 has been deposited on the right than has beendeposited on the left of the different type moltenized wire 28. It iscontemplated that the depositional characteristics of simultaneouslysprayed streams may vary volumetrically; they may also be volumetricallybalanced as illustrated at least in FIG. 2A.

[0019] In one embodiment of the present invention, during the sprayingprocess the two guns 13 are not directed at the same location, but areinstead directed at points adjacent to one another as is shown in FIGS.2A-2D. Resultingly, the two metals, exemplarily zinc and copper, can beconfigured to establish what amounts to predominantly separate stripes54 of the respective metals as the guns 13 traverse the surfaces 43 uponwhich the molten metals are being deposited. Among others, it is forthis reason that the resulting tool is described as being composed of apseudo-alloy composite, and not an actual alloy such as brass as wouldbe the case when taking zinc and copper as the examples.

[0020] By maintaining the metals in their segregated state, a broaderrange of qualities can be obtained therefrom than when using a truealloy. Referring again to the example of brass, that alloy can only beestablished within particular percentage ranges of zinc with respectcopper. When maintained separately, the percentage composition of theresulting spray formed body may be composed of any combination rangingfrom predominantly zinc and little copper to predominantly copper andlittle zinc. In this way, the desired qualities of the two metals can beadvantageously exploited to the fullest extent. Regarding comparablespray formed compositions, those desired qualities can include bettertensile strength, better thermal conductivity, better hardness andbetter dimensional stability. At least in part, this better dimensionalstability is accomplished by controlling stress that is induced in theresulting spray formed body. The goal of stress control can also beaccomplished through the manipulation of the percentages of each of thedifferent metal types utilized to establish the psuedo-alloy orcomposite spray formed body.

[0021] It should be appreciated that zinc is a preferred metal to beutilized in spray form techniques that are to be carried out on suchmaster model substrates as wood, wax, plastic and other materialsvulnerable to the high temperatures associated with conventional sprayform techniques. The utilization of zinc is preferred because of thatelement's relatively low melting temperature. That is, if a high contentof zinc is utilized, then a generally lower application temperature willbe enabled at the master model.

[0022] A problem, however, with spray formed bodies having a high zinccomposition is that they are relatively soft, as opposed to othersprayed metals, thereby preventing tools formed by such metals frombeing used in such applications as stamping tools for metal pieces inwhich harder materials of construction are required.

[0023] The melting point for zinc is approximately 450 degrees Celsius.Compared to other metals and alloys, however, this is a relatively lowmelting temperature. Resulting, when the parameters at the spray gun 13are properly controlled, after being moltenized in the gun's arc, thesprayed zinc 34 may be cooled to a temperature as low as 50 degreesCelsius as it travels away from the gun and immediately upon strikingthe master model substrate 12. At this temperature, the zinc isquasi-molten because it partially solidifies in flight, but it stillreadily forms a metallic bond with surroundingly deposited metals.Interestingly, a quasi-molten metal having a temperature as low as 50degrees Celsius immediately after contact can actually be sprayed upon aperson without causing harm or discomfort, thereby permitting the personto serve as a master model.

[0024] With regard to master models 12 constructed from such low-heatresistant materials as wax and plastic, or those established usingstereo lithography, application temperatures below the 50-70 degreeCelsius range will typically be satisfactory for conducting spray formtechniques directly thereupon. The degree of cooling of the molten metalcan be controlled by, among other parameters, adjusting the distancebetween the guns 13 and the master model 12; adjusting the type,temperature and/or volume of pressured gas supplied as the carrier forthe moltenized metal; and the applied gun arc amperage and/or voltage.Still further, auxiliary cooling may be provided in the form of acooling fan that directs a flow of ambient or cooled air upon thearticle being spray formed.

[0025] In ordered to combat the undesirable characteristics experiencedwhen pure zinc is utilized in spray formed bodies that are intended tobe utilized for prototype or rapid tooling applications, the presentinvention strategically incorporates other metals thereby forming acomposite pseudo-alloy body. As discussed hereinabove, the establishmentof the composite is accommodated by the use of multiple guns 13 whichcan be independently controlled. The present invention appreciates theutility of incorporating steel 37 or copper 37 together with the zinc 34for obtaining a harder and stronger spray formed body or tool. Each ofthese metals, however, have substantially higher melting points thandoes zinc 34. Therefore, there is a limit to the percentage content ofthese non-zinc metals 37 that can be incorporated. The two competingparameters that must be balanced is the desire for a high content of thenon-zinc metal(s) 37 for hardness and durability in the resulting toolversus low application temperature at the master model 12 that isprimarily enabled by high zinc content.

[0026] The compositional layering enabled by spray form techniques mayalso be advantageously exploited. In order to accommodate thenecessarily low temperature required at the surface 43 of a master modelsubstrate 12 made exemplarily from wax, a high content zinc layer may beinitially sprayed upon the master model 12, with an increasingly highernon-zinc metal content being subsequently applied in the build-uplayers. It is within these subsequent layers that the pseudo-alloy ispredominantly established. The layers are in fact quite thin and therecan be a degree of intermix between adjacent layers.

[0027] The present invention advantageously manipulates thesespray-variables for increasing the hardness, strength and durability ofa tool manufactured by the instant spray form techniques, while at thesame time, minimizing internal stress within the tool body. Byminimizing the internal stress either by avoiding original inducement ofstress (stress-free) or by negating/canceling internal stresses withinthe body (no-stress), shape-distortion in the finished article isavoided. This can be especially important as between the multiplebuilt-up layers in order to avoid warping of the article. Minimizedstress is also desirable in order to prevent the spray formed body fromtending to pull away from the master model substrate 12.

[0028] One way for controlling the stress in a spray formed body is tocontrol the temperature at which the molten metal is first applied tothe master model substrate 12, and also in the subsequent layers as thebody is built up. The general goal is to minimize the differentialbetween the temperature at which the molten metal 34,37 strikes the bodyand the temperature to which it ultimately cools. By minimizing thisdifferential, there is a minimized degree of contraction due to cooling.

[0029] In practice, the spray guns 13 may be moved back and forth acrossthe article being spray formed in substantially straight lines so that“stripes” of the respective sprayed metals 34,37 are established. Insome instances, commingled bands of pseudo-alloy are establishedtherebetween. After a layer or one series of stripes has been completed,the master model substrate 12 may be indexed to a transverse position,exemplarily to approximately 90 degrees from which a perpendicularstripe pattern is established in the subsequent application or layer. Byestablishing such lattice configurations between the layers, at leastsome of the stress that is induced is compensated for by the opposedpatterns and fosters the desired no-stress characteristics in theresulting spray formed body.

[0030] The internal stresses of the established spray formed article arealso controlled by varying the relative volumetric applications of thedifferent metals 34,37 as exemplarily shown in FIG. 1. For instance,some metals will create contractive forces within the finished productas a result of cooling, while others will experience expansion due totransformations upon cooling and impose compactive effects within thebody. By purposeful manipulation, the relative quantities among theseveral metals 34,37 being applied from the different guns 13 can beadjusted so that as close to zero stress results in the finished articleas possible. Additionally, this minimization of stress insures that thespray formed article does not pull away from the master model 12 duringthe cooling process.

[0031] Through the course of experimentation, preferred ranges for bothdroplet 40 landing temperature and elemental composition of a finishedarticle have been discovered. In trials, pseudo-alloys have been createdusing zinc 34 and copper 37, as well as zinc 34 and steel 37. Withrespect to each combination, a target temperature of 50 degrees Celsiushas been identified, with an acceptable range being defined thereaboutfrom 32 degrees Celsius to 60 degrees Celsius. For zinc and copper(Zn/Cu) and zinc and steel (Zn/Fe) combinations, a particularlyadvantageous range of constituent composition percentages, measured on aby-weight basis, has been identified as ranging between 60/40 and 54/46.These compositions have rendered hardness values in the range of 60 to68 for the zinc and copper combination and 85 to 95 for the zinc andsteel combination. For comparison purposes, it should be appreciatedthat zinc alone would have a hardness value of 46 to 52 on the utilizedscale for this same application temperature range. In the presentexample, the steel utilized in the zinc and steel combination is anoff-the-shelf product that contains 0.8 carbon steel.

[0032] Regarding the goals of spray form techniques according to thepresent invention, there are several areas of suitable utilization. Onegroup is prototype stamping tools, low-volume production stamping toolsand certain mass production stamping tools. The resulting tools can,however, be relatively soft as compared to tools constructed from truealloys and are typically not suited for long-range continuous massproduction metal stamping processes. They are, however, especiallysuited for utilization in plastic blow molding processes, plasticinjection molding processes, and as serving as lay-up tools utilized inaircraft construction. In these latter cases, sufficient hardness iseasily established using the pseudo-alloys of zinc described hereinhaving steel, copper and/or similar elements added thereto.

[0033] As intimated hereinabove, in at least one embodiment the presentinvention takes the form of a method for spray forming an article. Themethod includes spraying a plurality of metal streams 25 upon a low-heatresistant model 12 and thereby forming a spray formed article. Each ofthe plurality of metal streams 25 is composed of moltenized droplets 40,and as between the plurality of metal streams 25, each is composed ofdifferent constituent elements in the spray form process, conditions ofthe metal streams 25 are controlled, and particularly around the timethat the droplets 40 strike first, the exterior receiving surface 43 ofthe model 12, and then the exposed outside surfaces 43 of the sequentialmetal layers as they are built-up in the spray form process. The sprayconditions are controlled in such a manner that the individual metaldroplets 40 forming the metal streams 25 remain substantially segregate;that is to say, touching one another, but without intermixing acrossdroplet surface boundaries. The segregated state is maintained throughout solidification so that the resulting spray formed article iscomposed at least partially of psuedo-alloy; that is, commingleddroplets 40 of different elemental metals, but without intermixing intotrue allows. In this manner, the droplets 40 are held together based onmechanically adhesion occurring when the semi-molten droplets 40 comeinto contact with one another. In another aspect, the invention includesthe control of the relative proportions utilized of each of theplurality of metal streams 25 in a manner that institutes prescribedperformance characteristics in the spray formed article thereby assuringthat the spray formed article is suitable for intended use.

[0034] In practice, feed-wire 28 or 31 is fed respectively to arc guns13 that establish the plurality of metal streams 25. The feed-wires28,31 are selected so that one pair of wire strands 28 going to one gun13 is composed predominantly of zinc metal and another pair of wirestrands 31 going to the other gun 13 are composed predominantly ofnon-zinc metal. In a preferred embodiment, the predominantly non-zincmetal feed-wire 31 has sufficient amounts of steel, copper or othersuitable metal to establish a wear resistant mold that can be used insuch manufacturing processes as blow molding and/or injection molding.Still further, a low-volume stamping tool may be similarly spray formed.

[0035] The relative proportions may be manipulated and varied betweenthe plurality of metal streams 25 with regard to elemental constituentmake-up during the spraying process. In this way, the user can tailorthe characteristics of the spray formed article for custom applications.

[0036] Varying the elemental make-up can also be used to establish ano-stress spray formed article through manipulating the relativeproportions of the plurality of metal streams 25 to cancel out anyinduced stress. Similarly, a stress-free spray formed article may beformed through control of the relative proportions of the differentconstituent elements.

[0037] In one practice according to the present invention which isillustrated in FIGS. 2A-2D, each of the plurality of metal streams 25 isaimed at different, but adjacent locations on the spray formed article.In such a spaced configuration 50, these different, but adjacentlocations on the spray formed article are spaced sufficiently far apartthat a gap-space 52 is maintained between simultaneously sprayed metalstreams 34,37. Throughout the process, each of the plurality of metalstreams 25 is sprayed across the spray formed article so that discretemetal stripes 54 are formed on the exposed receiving surfaces 43. Thesesurfaces 43 include not only the exterior surface 43 of the master model12, but also the exposed surface 43 of each subsequent layer of sprayformed metal that is applied thereto. The metal stripes 54 are spacedapart so that parallel and discrete metal stripes 54 with essentially nooverlap therebetween are established across the spray formed article. Asindicated above, the orientation of the model 12 may be altered prior toa subsequent layer's application, or the guns 13 may be manipulated in across-wise direction to the previous. In either event, the parallel anddiscrete metal stripes 54 of sequential layers are applied in a latticeconfiguration 56 for minimizing stress-induced shape distortion in thefinished spray formed article. The angle at which the latticeconfiguration is established may vary, therefore, within an acceptablerange, the cross-wise metal stripes may be longitudinally transverselyoriented as shown in FIG. 2C in which a transverse lattice configuration58 is established. In one particularly preferred embodiment, theorientation of the crossing metal stripes is perpendicularly oriented asshown in FIG. 2D thereby establishing a perpendicular latticeconfiguration 59.

[0038] In an exemplary embodiment, the non-zinc feed-wire 31 iscomprised of sufficient amounts of steel to establish the spray formedarticle as a low-volume stamping tool. The wire strands 31 are chosen sothat it has sufficient amounts of the non-zinc metal, exemplarily steel,to establish a spray formed article capable of being used as alow-volume stamping tool.

[0039] As indicated above, but for clarity within the context of theteachings of the method(s) of the present invention, applicationconditions regarding the plurality of metal streams 25 are controlled sothat immediately upon striking the exposed receiving surfaces 43, themetal droplets 40 have a temperature ranging from approximately 32degrees to 60 degrees Celsius thereby avoiding softening and combustinga low-heat resistant model 12. A preferred temperature has been found tobe approximately 50 degrees Celsius, which avoids softening, and/orcombusting a low-heat resistant model 12.

[0040] In one configuration that is illustrated in FIGS. 3A-3D, theaiming of the metal streams 25 causes a segregation interface 62 to beestablished between the simultaneously sprayed metal streams 25. Thereis essentially no overlap between the simultaneously sprayed pluralityof metal streams 25. As the metal is sprayed across the spray formedarticle, segregated, but interfacing metal stripes 64 are formed. Aninterfaced relationship 60 is maintained between the metal stripes 64 sothat the parallel metal stripes 64 touch one another, but there isessentially no overlap between the metal stripes 64. As in the spacedapart embodiment, the parallel metal stripes 64 may be arranged into alattice configuration 66 that may be transverse 68 or perpendicular 69for minimizing stress-induced shape distortion in the finished sprayformed article.

[0041] In an alternative execution of the method of the presentinvention demonstrated in FIGS. 4A-4D, an overlapping interface 72 maybe established between simultaneously sprayed metal streams therebyestablishing an interposed psuedo-alloy zone. During the spray process,an overlapped inter-relationship or configuration 70 is maintainedbetween overlapping metal stripes 74 so that the parallel metal stripes74 overlap one another thereby establishing an interposed psuedo-alloystripe-zone 72. As in the other embodiments, the overlapping metalstripes 74 may also be arranged into a lattice configuration 76 that maybe transverse 78 or perpendicular 79 for minimizing stress-induced shapedistortion in the finished spray formed article.

[0042]FIG. 5A-5D show yet another possible execution of the presentinvention in which a substantially commingled configuration 80 isestablished having a commingled interface 82 formed by commingled metalstripes 84. In this configuration, the target location for each of thespray streams 25 is substantially identical, but possibly with a slightoffset. As with the other embodiments, the commingled metal stripes 84may also be arranged into a lattice configuration 86 that may betransverse 88 or perpendicular 89 for minimizing stress-induced shapedistortion in the finished spray formed article.

[0043] A method for establishing a dimensionally stable spray formedarticle has been variously described. These and other variations, whichwill be appreciated by those skilled in the art, are within the intendedscope of this invention as claimed below. As previously stated, detailedembodiments of the present invention are disclosed herein; however, itis to be understood that the disclosed embodiments are merely exemplaryof the invention that may be embodied in various forms.

1. A method for spray forming an article, said method comprising:spraying a plurality of metal streams upon a low-heat resistant modeland thereby forming a spray formed article, each of said plurality ofmetal streams being composed of moltenized droplets, and as between theplurality of metal streams, each is composed of different constituentelements; controlling application conditions of said plurality of metalstreams upon exposed receiving surfaces during the spraying process sothat individual metal droplets of said plurality of metal streams remainsubstantially segregate through out solidification and thereby establishsaid spray formed article composed at least partially of a psuedo-alloy;and controlling relative proportions between said plurality of metalstreams composed of different constituent elements in a manner thatinstitutes prescribed performance characteristics in said spray formedarticle thereby assuring that said spray formed article is suitable forintended use.
 2. The method as recited in claim 1, further comprising;supplying feed-wire to arc guns that establish said plurality of metalstreams; and selecting said feed-wire so that a strand of wire iscomposed predominantly of zinc metal and another strand of wire iscomposed predominantly of non-zinc metal.
 3. The method as recited inclaim 2, further comprising: selecting said predominantly non-zinc metalfeed-wire to comprise sufficient amounts of steel to establish saidspray formed article as a wear resistant molding form. selecting saidpredominantly non-zinc metal feed-wire to comprise sufficient amounts ofcopper to establish said spray formed article as a low-volume stampingtool.
 5. The method as recited in claim 1, further comprising: varyingsaid relative proportions between said plurality of metal streamscomposed of different constituent elements during the spraying processand thereby customizing characteristics of said spray formed article. 6.The method as recited in claim 5, further comprising: establishing ano-stress spray formed article by manipulating said variation of saidrelative proportions between said plurality of metal streams composed ofdifferent constituent elements during the spraying process.
 7. Themethod as recited in claim 5, further comprising: forming a stress-freespray formed article by manipulating said variation of said relativeproportions between said plurality of metal streams composed ofdifferent constituent elements during the spraying process.
 8. Themethod as recited in claim 1, further comprising: aiming each of saidplurality of metal streams at different, but adjacent locations on saidspray formed article; and spacing said different, but adjacent locationson said spray formed article sufficiently far apart that a gap-space ismaintained between simultaneously sprayed metal streams.
 9. The methodas recited in claim 8, further comprising: spraying each of saidplurality of metal streams across said spray formed article so thatdiscrete metal stripes are formed on the exposed receiving surfaces; andspacing said metal stripes apart so that parallel and discrete metalstripes with essentially no overlap therebetween are established acrosssaid spray formed article.
 10. The method as recited in claim 9, furthercomprising: arranging said parallel and discrete metal stripes into alattice configuration for minimizing stress-induced shape distortion inthe finished spray formed article.
 11. The method as recited in claim10, further comprising: configuring said lattice configuration so thatcrossing metal stripes are longitudinally transversely oriented.
 12. Themethod as recited in claim 11, further comprising: configuring saidlongitudinally transversely oriented crossing metal stripes to beperpendicularly oriented.
 13. The method as recited in claim 1, furthercomprising: supplying feed-wire to arc guns that establish saidplurality of metal streams; and selecting said feed-wire so that astrand of wire is composed predominantly of zinc metal and anotherstrand of wire is comprised of sufficient amounts of steel to establishsaid spray formed article as a low-volume stamping tool.
 14. The methodas recited in claim 1, further comprising, supplying feed-wire to arcguns that establish said plurality of metal streams, each of saidplurality of metal streams being composed of different constituentelements; selecting said feed-wire so that a strand of wire is composedpredominantly of zinc metal and another strand of wire is comprised ofnon-zinc metal; and choosing said strand of wire that comprises non-zincmetal to have sufficient amounts of said non-zinc metal to establishsaid spray formed article as a low-volume stamping tool.
 15. The methodas recited in claim 1, further comprising: controlling applicationconditions of said plurality of metal streams so that immediately uponstriking said exposed receiving surfaces, said metal droplets have atemperature ranging from approximately 32 degrees to 60 degrees Celsiusthereby avoiding softening and combusting a low-heat resistant model.16. The method as recited in claim 1, further comprising: controllingapplication conditions of said plurality of metal streams so thatimmediately upon striking said exposed receiving surfaces, said metaldroplets have a temperature of approximately 50 degrees Celsius therebyavoiding softening and combusting a low-heat resistant model.
 17. Themethod as recited in claim 1, further comprising: supplying feed-wire toarc guns that establish said plurality of metal streams; selecting saidfeed-wire so that a strand of wire is composed predominantly of zincmetal and another strand of wire is composed predominantly of non-zincmetal; and controlling wire feed conditions so that said spray formedarticle, on a by-weight basis, comprises between 54 and 60 percent zincmetal and between 40 and 46 percent non-zinc metal, respectively. 18.The method as recited in claim 1, further comprising: aiming each ofsaid plurality of metal streams at different, but adjacent locations onsaid spray formed article; and spacing said different, but adjacentlocations on said spray formed article so that a segregation interfaceis established between simultaneously sprayed plurality of metalstreams, but there is essentially no overlap between said simultaneouslysprayed plurality of metal streams.
 19. The method as recited in claim18, further comprising: spraying each of said plurality of metal streamsacross said spray formed article so that segregated, but interfacingmetal stripes are formed on the exposed receiving surfaces; andmaintaining an interfacing relationship between said metal stripes sothat parallel metal stripes touch one another, but there is essentiallyno overlap between said metal stripes.
 20. The method as recited inclaim 19, further comprising: arranging said parallel metal stripes intoa lattice configuration for minimizing stress-induced shape distortionin the finished spray formed article.
 21. The method as recited in claim1, further comprising: aiming each of said plurality of metal streams atdifferent, but adjacent locations on said spray formed article; andspacing said different, but adjacent locations on said spray formedarticle so that an overlapping interface is established betweensimultaneously sprayed metal streams thereby establishing an interposedpsuedo-alloy zone.
 22. The method as recited in claim 21, furthercomprising: spraying each of said plurality of metal streams across saidspray formed article so that overlapping metal stripes are formed on theexposed receiving surfaces of said spray formed article; and maintainingan overlapped inter-relationship between said metal stripes so thatparallel metal stripes overlap one another thereby establishing aninterposed psuedo-alloy stripe-zone. 23.The method as recited in claim22, further comprising: arranging said parallel metal stripes into alattice configuration for minimizing stress-induced shape distortion inthe finished spray formed article.